The present invention relates to a semiconductor device, and more particularly, to a bonding pad for preventing a pad from peeling in a ball bonding, and a method for fabricating the same.
In the fabrication of a semiconductor device, wire bonding in a packaging process is an electrical interconnection technique. In the wire bonding, a metal pad of a bonding pad part provided in a chip is electrically interconnected to a lead frame for connection to an external device. For example, in the wire bonding, a ball bonding is performed over a metal pad. The bonding pad part to be bonded includes multiple metal layers and insulation layers filling gaps between the multiple metal layers.
FIG. 1 illustrates a cross-sectional view of a typical bonding pad structure, and FIG. 2 illustrates a cross-sectional view for explaining a technical limitation of a typical ball bonding.
Referring to FIG. 1, the typical bonding pad includes a first metal layer M1, a second metal layer M2, and a third metal layer M3. A first insulation layer IMD1 is formed between the first metal layer M1 and the second metal layer M3, and a second insulation layer IMD2 is formed between the second metal layer M2 and the third metal layer M3. A ball bonding is performed on the uppermost layer, that is, the third metal layer M3.
In a subsequent package fabrication process, as illustrated in FIG. 2, a ball bonding 11 is performed on a center of the third metal layer M3 in the bonding pad of FIG. 1.
However, pressure generated by the ball bonding 11 is transferred to the second insulation layer IMD2 and the second metal layer M2, and a repulsive force 12 is transferred to edges of the third metal M3. The repulsive force 12 causes a pad peeling 13 at the edges of the third metal layer M3, leading to a ball bonding failure. That is, a peeling phenomenon occurs so that an attachment force of the pad is weakened and the pad is peeled off.